There is a known sample surface measuring apparatus, called a Friction Force Microscope (FFM), or a Lateral Force Microscope (LFM) as a technology capable of material evaluation on nanometer scale and the like through the measurement of friction force distribution on the surface of the sample (for example, refer to Document 1: Japanese Patent Application Laid-Open No. 2000-171381, Document 2: Japanese Patent Application Laid-Open No. 2000-258331). In the friction force microscope, as illustrated in FIG. 8 for example, a fine cantilever 6 (100 μm order of length and 1 μm order of thickness) having a lever section 62 fixed to a base section 60 is used as a measurement probe, and the surface of the sample S is measured by using a probe tip 61 having a sharp tip of several nanometers or smaller size, provided at an end portion of the lever section 62.
That is, the cantilever 6 scans the surface of the sample along a scanning direction orthogonal to a support axis direction which is a long axis direction of the lever section 62 and a probe tip axis direction which is a direction of protrusion of the probe tip 61. During scanning, a friction force (lateral force) is applied to the probe tip 61 in the direction of the scanning axis (lateral axis), thereby inducing “torsion” on the lever section 62. Also depending on the surface shape of the sample, a load (vertical force) is applied to the probe tip 61, thereby inducing “deflection” on the lever section 62. By measuring the torsion and the deflection generated on the lever section 62, the force in the two directions, lateral force and vertical force, generated by the scanning of the sample can be determined, thus being able to acquire surface information of the sample. Furthermore, based on the ratio of the lateral force and the vertical force, a friction coefficient on the sample surface can be determined.
By using the above measuring method, for example, for the sample of a composite material such as a reinforced plastic made from a resin reinforced with carbon fibers used for airframes of aircraft and the like, or a glass containing dispersed fine particles to provide the glass with new functions, a distribution of constituent materials in the composite material can be investigated by preparing a cross-sectional surface of the sample, and measuring the friction coefficient distribution on the surface by using the above apparatus. Further, the friction characteristics and the lubrication characteristics of the material surface can be measured at nanometer scale by measuring the lateral force and the vertical force.    Patent Document 1: Japanese Patent Application Laid-Open No. 2000-171381    Patent Document 2: Japanese Patent Application Laid-Open No. 2000-258331    Patent Document 3: Japanese Patent Application Laid-Open No. 2000-258332    Patent Document 4: Japanese Patent Application Laid-Open No. H11-166823    Patent Document 5: Japanese Patent Application Laid-Open No. 2001-56281    Non-Patent Document 1: B. W. Chui et al., Applied Physics Letters, Vol. 72, No. 11, pp. 1388-1390 (1998)    Non-Patent Document 2: S. A. Joyce and J. E. Housion, Rev. Sci. Instrum. Vol. 62, No. 3, pp. 710-715 (1991)